| The authors conducted bedload-discharge measurement using an Acoustic Doppler Current Profiler (ADCP)、a modified Toutle River-2 bedload sampler (TR-2β) originally fabricated by the United States Geological Survey (USGS)、and a water-sediment sampler modified based on a suspended sediment sampler. Results from field measurements during minor flooding at two different sites show that 1) not only TR-2βbut also the water-sediment sampler is necessary to observe the size distribution of sediment particles、though appropriate volumes of bedload discharge cannot be obtained by those two sediment samplers in contrast to shear velocity. They also show that 2) ADCP performed better in the measurements than the sediment samplers. Additionally、the authors described the characteristics of bedload discharge as being unsteady and showing a cross-sectional distribution. Finally the authors proposed an observation method based on the findings and suggested the applicability of the current methods in terms of hydraulic condition. |
